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ToxFAQs™ for Carbon Tetrachloride

This fact sheet answers the most frequently asked health questions about carbon tetrachloride. For more
information, you may call the ATSDR Information Center at
1-888-422-8737. This fact sheet is one in a series of summaries
about hazardous substances and their health effects. This
information is important because this substance may harm you.
The effects of exposure to any hazardous substance depend
on the dose, the duration, how you are exposed, personal traits
and habits, and whether other chemicals are present.

Highlights

Carbon tetrachloride
does not occur naturally. Exposure to this substance results
mostly from breathing air, drinking water, or coming in
contact with soil that is contaminated with it. Exposure
to very high amounts of carbon tetrachloride can damage
the liver, kidneys, and nervous system. Carbon tetrachloride
can cause cancer in animals. Carbon tetrachloride has
been found in at least 425 of the 1,662 National Priority
List sites identified by the Environmental Protection
Agency (EPA).

What is carbon tetrachloride?

Carbon tetrachloride is a manufactured
chemical that does not occur naturally. It is a clear liquid
with a sweet smell that can be detected at low levels. It
is also called carbon chloride, methane tetrachloride, perchloromethane,
tetrachloroethane, or benziform.

Carbon tetrachloride is most often found
in the air as a colorless gas. It is not flammable and does
not dissolve in water very easily. It was used in the production
of refrigeration fluid and propellants for aerosol cans, as
a pesticide, as a cleaning fluid and degreasing agent, in
fire extinguishers, and in spot removers. Because of its harmful
effects, these uses are now banned and it is only used in
some industrial applications.

How can carbon tetrachloride affect my health?

High exposure to carbon tetrachloride
can cause liver, kidney, and central nervous system damage.
These effects can occur after ingestion or breathing carbon
tetrachloride, and possibly from exposure to the skin. The
liver is especially sensitive to carbon tetrachloride because
it enlarges and cells are damaged or destroyed.

Kidneys also are damaged, causing a build
up of wastes in the blood. If exposure is low and brief, the
liver and kidneys can repair the damaged cells and function
normally again. Effects of carbon tetrachloride are more severe
in persons who drink large amounts of alcohol.

If exposure is very high, the nervous
system, including the brain, is affected. People may feel
intoxicated and experience headaches, dizziness, sleepiness,
and nausea and vomiting. These effects may subside if exposure
is stopped, but in severe cases, coma and even death may occur.

There have been no studies of the effects
of carbon tetrachloride on reproduction in humans, but studies
in rats showed that long-term inhalation may cause decreased
fertility.

How likely is carbon tetrachloride to cause cancer?

Studies in humans have not been able
to determine whether or not carbon tetrachloride can cause
cancer because usually there has been exposure to other chemicals
at the same time. Swallowing or breathing carbon tetrachloride
for years caused liver tumors in animals. Mice that breathed
carbon tetrachloride also developed tumors of the adrenal
gland. The Department of Health and Human Services (DHHS)
has determined that carbon tetrachloride may reasonably be
anticipated to be a carcinogen. The International Agency for
Research on Cancer (IARC) has determined that carbon tetrachloride
is possibly carcinogenic to humans, whereas the EPA determined
that carbon tetrachloride is a probable human carcinogen.

How can carbon tetrachloride affect children?

The health effects of carbon tetrachloride
have not been studied in children, but they are likely to
be similar to those seen in adults exposed to the chemical.
We do not know whether children differ from adults in their
susceptibility to carbon tetrachloride.

A few survey-type studies suggest that
maternal drinking water exposure to carbon tetrachloride might
possibly be related to certain birth defects. Studies in animals
showed that carbon tetrachloride can cause early fetal deaths,
but did not cause birth defects. A study with human breast
milk in a test tube suggested that it would be possible for
carbon tetrachloride to pass from the maternal circulation
to breast milk, but there is no direct demonstration of this
occurring.

Is there a medical test to show whether I've been exposed to carbon tetrachloride?

Several sensitive and specific tests
are available to measure carbon tetrachloride in exposed persons.
The most convenient way is simply to measure carbon tetrachloride
in the exhaled air. Carbon tetrachloride also can be measured
in blood, fat, or other tissues. These tests are not usually
done in the doctor's office because they require special equipment.
Although these tests can show that a person has been exposed
to carbon tetrachloride, the results cannot be used to reliably
predict whether any adverse health effect might result. Because
carbon tetrachloride leaves the body fairly quickly, these
methods are best suited to detecting exposures that have occurred
within the last several days.

Has the federal government made recommendations to protect human health?

The EPA has set a limit for carbon tetrachloride
in drinking water of 5 parts of carbon tetrachloride per billion
parts of water (5 ppb). The EPA has also set limits on how
much carbon tetrachloride can be released from an industrial
plant into waste water and is preparing to set limits on how
much carbon tetrachloride can escape from an industrial plant
into outside air.

The Occupational Safety and Health Administration
(OSHA) set a limit of 10 ppm for carbon tetrachloride in workplace
air for an 8-hour workday, 40-hour workweek.

ATSDR can also tell you the location of occupational and environmental health clinics. These clinics specialize in
recognizing, evaluating, and treating illnesses resulting from exposure to hazardous substances.